[prototype] AssetExecutionContext partition methods on sub context

[jamiedemaria]

Summary & Motivation

This PR is a prototype for a potential API for partition methods on the AssetExecutionContext. This version moves all of the partition related properties and methods to a PartitionContext object so that they are grouped and made a more distinct from other context methods

Hooli PR - dagster-io/hooli-data-eng-pipelines#61
DOP PR - https://github.com/dagster-io/internal/pull/7931
Nice things about this design:

• methods will be grouped together in the API docs since they will all fall under the PartitionContext.
• Similarly, users will know they aren't missing a partition method in the long list of context methods

issues with this API design:

• The naming right now isn't great, it involves a lot of repetition of partition. But the removal of some of the partitions may sacrifice clarity

How I Tested These Changes

[jamiedemaria]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
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Current dependencies on/for this PR:

• master
  • PR Only have one kind of context for direct invocation #17554
    • PR duplicate op context methods on asset context  #18573
      • PR deprecate methods on AssetExecutionContext that can be found via the DagsterRun object #17339
        • PR Direct invocation asset execution context #18549
          • PR deprecate asset_partition_*_for_output on AssetExecutionContext #19436
            • PR [docs] remove asset_partition_*_for_output from docs #19437
              • PR deprecate op related methods from AssetExecutionContext #19441
          • PR Make upstream asset materialization events available on the context #18971
            • PR [wip] store the tags fetched by data versioning so we can use them for upath io manager #19324
              • PR [UPath I/O managers] special case handling of None outputs #18820
            • PR Make input partitions methods based on asset key not input name #19027
              • PR Support partitioned assets for fetching latest AssetMaterializations #19286
              • PR [do not merge] base example to showcase new apis #19199
                • PR [prototype] sub-context for each upstream dependency  #19283
                • PR [prototype] AssetExecutionContext partition methods on sub context #19236 👈
                • PR [prototype] AssetExecutionContext partition methods given as named tuple #19037
                • PR [prototype] AssetExecutionContext partition methods directly on the context #19032
            • PR [wip] two execution contexts with minimal changes #18543
              • PR [wip] see wht needs to change when asset context is no longer an op context #18553
        • PR support Asset and Op ExecutionContexts in standard execution path #17972
          • PR [wip] add AssetExecutionContext to direct invocation #18044

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